10 
large part to the physical influence of the clay, in so far as it governs 
the concentration and composition of the soil solution. 1 
Manganese. — The manganese content of the grains apparently in- 
creases with the size of the soil particles. Only traces of this element 
are found in clay, while appreciable amounts are present in coarse 
sand. It may be mentioned in this connection that a soil of high 
manganese content always possesses a loose, sandy texture, although 
it may be surrounded on all sides by heavy clay types. 
Lime. — While lime is found in appreciable amounts in clay par- 
ticles, a result to be expected from its general properties, it is present 
in largest amount in the coarse grains. Lime is an extremely variable 
constituent in Hawaiian soils, and its presence or absence is in- 
fluenced to a marked degree by weathering agents. 
Magnesia. — Magnesia, being similar to lime in most of its prop- 
erties, is found distributed in the soil grains with relation to size 
very much in the same way as lime. Hawaiian soils are almost 
uniformly higher in magnesia than in lime. Lime is apparently 
present in larger amounts than magnesia in the clay particles. 
PROPERTIES OF THE SOIL PARTICLES. 
Coarse sand. — Under this head are classed all particles from 0.2 
to 1 millimeter in diameter. It might be expected that these particles 
would more closely resemble lava in composition, since disintegra- 
tion has not progressed far, but in most cases leaching has been so 
complete that there is little difference in composition whether the 
soil is derived from volcanic ash or lava. Soil No. 291 is a trans- 
ported type derived from volcanic ash, and the sand grains seem to 
be composed primarily of a complex magnesium silicate. No. 292 
is a soil derived from the same ash but through the action of differ- 
ent weathering agents. 
Fine sand. — This division includes all grains ranging in size from 
0.04 to 0.2 millimeter in -diameter. In passing from coarse to fine 
sand, the soil particles show a tendency toward an increase in silica, 
titanium, and iron, and a decrease in alumina. In certain types in 
which titanium is abundant, silica is present in very small amounts 
in the coarse particles. 
Silt. — The next division consists of particles ranging in size from 
0.01 to 0.04 millimeter in diameter. In passing from fine sand to silt 
there is a further increase in silica content, while the iron and alumina 
present no uniform change, some samples showing an increase in 
these constituents, others a decrease. 
Fine silt. — These particles vary in size from 0.002 to 0.01 millimeter 
in diameter. The silica content varies from 20.70 to 44.75 per cent, 
i Hawaii Sta. Buls. 35 (1914), 38 (1915), 40 (1915). 
